This invention relates to polyurethane/polyurea materials. These polyurethane/polyureas comprise the reaction product of (A) a polyisocyanate prepolymer, and (B) an isocyanate-reactive component comprising (1) at least one aromatic diamine compound, optionally in the presence of (C) one or more catalysts. The (A) polyisocyanate prepolymers herein comprise the reaction product of (1) at least one (cyclo)aliphatic polyisocyanate with (2) an organic compound having 1.8 to 5 hydroxyl groups and an hydroxyl equivalent weight of 150 to 2000, and is selected from the group consisting of OH functional polybutadienes, OH-functional polyalkylene phthalates, OH-functional polyalkylene isophthalates, OH-functional polyalkylene terephthalates and mixtures thereof.
Various light stable cast elastomers and processes for the production of these elastomers are known and described in the art. See, for example, U.S. Pat. Nos. 3,755,262, 3,866,242, 4,153,777, 4,404,353 and 4,808,690, and German Offenlegungsschrift 2, 109,901.
Transparent high-impact polyurethane products are disclosed by U.S. Pat. No. 3,755,262. These products may be elastomeric or non-elastomeric in nature. Suitable liquid polyurethane reaction mixtures for preparing these optical polyurethanes are made by the one-shot or prepolymer method. Preferred mixtures comprise a non-aromatic polyisocyanate and a reactive hydrogen containing polyol having an average of more than two hydroxyl groups per molecule and molecular weights of up to about 800.
U.S. Pat. No. 3,866,242 discloses protective shields consisting of a polyurethane, shaped in the contour of a clipboard, windshield, face shield, etc. These polyurethanes are described as being transparent and having excellent optical clarity. Suitable polyurethanes are prepared by reacting a polyester glycol or a polyether glycol with methylenebis(cyclo-hexylisocyanate) to form a prepolymer, and reacting this prepolymer with a primary amine group containing compound, preferably one having a methylene bridge between two aromatic rings such as methylenebis(2-chloroaniline).
U.S. Pat. No. 4,153,777 describes polyurethanes having improved physical properties. This reference specifically discloses non-porous polyurethanes which exhibit good optical clarity and resistance to weathering, ultra-violet and thermal exposure. These polyurethanes comprise an isocyanate-terminated prepolymer which is formed by first reacting the isocyanate with water, and then with a polyol to form the prepolymer. This prepolymer is then chain extended or crosslinked to form the cured polyurethane. Suitable isocyanates include (cyclo)aliphatic isocyanates and suitable chain extenders and crosslinkers include compounds such as 1,4-butanediol and trimethylolpropane.
High heat distortion temperature transparent polyurethanes which are highly crosslinked are described by U.S. Pat. No. 4,808,690. These comprise a prepolymer prepared from a polyisocyanate and at least one multifunctional hydroxy containing intermediate, with a polyol curing component. Suitable multifunctional hydroxyl containing intermediates include polyhydric alcohols, polyester polyols and blends thereof. Suitable polyisocyanates include (cyclo)aliphatic polyisocyanates, and the polyol curing component can be a polyester or a polyhydric alcohol.
Other polyurethane, polyurethane/urea or polyurea materials are disclosed in, for example, U.S. Pat. Nos. 5,510,445, 5,646,230, 5,714,562 and 6,174,984. These materials may be polyurethanes as in U.S. Pat. No. 5,714,562; polyurethane/ureas in as U.S. Pat. No. 5,646,230 and U.S. Pat. No. 6,174,984; or polyureas as in U.S. Pat. No. 5,510,445.
U.S. Pat. No. 6,174,984 discloses clear resilient polyurethane/polyurea elastomers. These elastomers comprise the reaction product of A) a prepolymer of at least one diisocyanate and at least one polyether polyol, having a free diisocyanate content of less than 1% of the prepolymer, B) at least one alkylated aromatic diamine in a quantity sufficient to react with about 50 to 105% of the available isocyanate content in the prepolymer, and C) at least one organic acid catalyst in a quantity sufficient to reduce the pot life to no more than two minutes. These elastomers possess high resilience and clarity.
Polyurea elastomers prepared by a one-step process are described in U.S. Pat. No. 5,510,445. The process comprises reacting (a) one or more (cyclo)aliphatic diisocyanates, (b) one or more liquid amine-terminated polymers containing at least two aromatically bound isocyanate-reactive primary or secondary amine groups and/or aliphatically bound isocyanate-reactive secondary amino groups and having a molecular weight of from 400 to 6,000, and (c) one or more aromatic diamine chain extenders having a molecular weight of from 108 to 399, optionally in admixture with one or more crosslinkers. Suitable diisocyanates include dicyclohexylmethane-4,4′-diisocyanate (rMDI) and prepolymers thereof. DETDA is disclosed as a suitable aromatic diamine chain extender.
U.S. Pat. Nos. 5,811,506 and 6,258,917 describe extrudable thermoplastic urea-extended polyurethanes. The polyurethane/polyureas in U.S. Pat. No. 5,811,506 comprise the reaction product of (a) a polyurethane prepolymer, (b) at least one first diamine curing agent, and (c) at least one second diamine curing agent that is different from the first diamine curing agent. Polyurethane/polyureas of U.S. Pat. No. 6,258,917 comprise the reaction product of (a) a polyurethane prepolymer, and (b) at least one diamine curing agent selected from the group consisting of 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene, 4,4′-methylene-bis(2-6-diisopropylaniline), trimethylene glycol di-para aminobenzoate and mixtures thereof. These polyurethane/polyureas have a Shore A hardness of 72 to 84, a DMA Tg of −80° C. or less and a TMA softening point of 205 to 208° C.
Polyurethane materials are also disclosed in U.S. Pat. Nos. 5,962,617 and 6,127,505. In U.S. Pat. No. 5,962,617, these comprise the reaction product of (a) a polyurethane prepolymer prepared by reacting methylene-bis(cyclohexyl isocyanate) with an OH-containing intermediate having a MWw of 500 to 1200, in an equivalent ratio of 2.5 to 4.0 NCO:1.0 OH, and (b) an aromatic diamine curing agent which has two aromatic ring groups attached by a methylene group, in which each aromatic ring is substituted by one NH2 group, and 3 of the remaining 4 positions on the aromatic ring are substituted, with the equivalent ratio of NH2:NCO ranging from 0.95:1.0 to 1.02:1.0.
U.S. Pat. No. 6,127,505 discloses that these polyurethane/polyurea materials comprise the reaction product of (a) a polyurethane prepolymer and (b) at least a first aromatic diamine curing agent. Suitable prepolymers are prepared by reacting an aliphatic or cycloaliphatic diisocyanate with an OH containing intermediate having a MWw of 400 to 2,000, in which the equivalent ratio is about 2.5 to 4.0 NCO/1.0 OH. The diamine curing agent is selected from 2,4-diamino-3,5-diethyl toluene, 2,6-diamino-3,5-diethyl toluene and mixtures thereof, in an equivalent ratio of NH2:NCO of 0.85:1.0 to 1.02:1.0.
Light stable, optically clear, one-shot urethane-urea elastomers and a process for their production are described in U.S. Pat. No. 6,562,932. This process comprises reacting a polyisocyanate or prepolymer thereof with an isocyanate-reactive component, in the presence of C) at least one organometallic catalyst. Suitable isocyanate-reactive components comprise (1) at least one aromatic diamine compound and (2) at least one organic compound having at least two hydroxyl groups and having a molecular weight of 62 to 6,000.
U.S. Pat. No. 6,939,939 discloses a polyurea/urethane material and a process for making this material. These polyurea/urethane materials are described as having good optical quality and high impact resistance. These comprise the reaction product of A) a urethane prepolymer prepared by reacting a first diisocyanate with a first polyol in amounts such that the prepolymer has an equivalent ratio of at least about 3 isocyanate groups per hydroxyl group; with B) a curing agent comprising (1) a hydroxyl-terminated extended chain polymer prepared by reacting a second diisocyanate with a second polyol in an amount such that the resultant polymer has an equivalent ratio of between about 3 and about 8 hydroxyl groups per isocyanate group; and (2) a diamine, in the presence of a catalyst.
U.S. Published Patent Application 2007/0100112 discloses optically clear polyurethane-ureas which comprise the reaction product of a (cyclo)aliphatic polisocyanate or prepolymer thereof with an isocyanate-reactive component that comprises one or more aromatic diamines that contain two primary amine groups, and one or more compounds containing two secondary amine groups which may be linked to aliphatic and/or aromatic moieties. Polyaspartic esters are particularly preferred compounds that contain two secondary amine groups.
Advantages of the presently claimed invention include the increased refractive index of the polyurethane/ureas which comprise OH-functional polybutadienes, OH-functional polyalkylene phthalates, OH-functional polyalkylene isophthalates and/or or OH-functional polyalkylene terepthalates compared to the polyurethane/polyurea materials previously known and/or described in the art, while maintaining desirable processing characteristics described in the art.